Blow molded plastic bottles have largely replaced the heavier glass bottles previously used for soft drinks, and the like. In a two liter bottle of plastic, the weight of the bottle itself is negligible as compared to the weight of a glass bottle of similar capacity. The first plastic bottles were generally two piece bottles comprising a pressure vessel portion and base which permitted the bottle to stand upright on shelves, and the like. The pressure vessel portion was typically of a tough, flexible plastic (e.g. polyester) which became resiliently rigid for gripping due to the internal pressure created by the carbon dioxide gas in the soft drink liquid contained therein. The bottom was hemispherical and the separate base was required in order for the bottle be able to stand by itself. The base was typically of a plastic such as polyethylene and is attached over the bottom of the pressure vessel portion with adhesive.
One alternative to a two-piece construction is to create a bottle having a so-called "champagne" base which resists the internal pressure. Inversion is a problem in such designs. In an attempt to avoid that problem, numerous bottle configurations have been proposed incorporating, for example, integral pressure-resistant ribs into the bottom of the bottle. Other prior art approaches are those disclosed in the inventor's own U.S. Pat. Nos. 4,780,257; 4,889,752; 4,927,679 which relate to a container having an annular peripheral chime surrounding an inward sloping base portion for resisting inversion of the base, caused by internal pressure, comprising an integral reinforcing ring incorporated into the base and running horizontally in the hoop direction. This reinforcing ring is placed in a location within the base to oppose inversion of the base.
More recently, bottle designs utilizing a petaloid base have been proposed. In all polyester (usually PET) bottles, weight is a very important consideration. Based on a conservative estimate of 5 billion bottles produced per year and a PET price of $(US) 1.54 per Kg ($(US) 0.70 per pound), a 1-2 gram decrease in the PET content of a bottle will save approximately $(US) 7-14 million per year.